1 files changed, 19 insertions, 0 deletions
diff --git a/bundle-plugin/src/main/scala/com/yahoo/container/plugin/util/Maps.scala b/bundle-plugin/src/main/scala/com/yahoo/container/plugin/util/Maps.scala
new file mode 100644
index 00000000000..7f12c5ba95d
--- /dev/null
+++ b/bundle-plugin/src/main/scala/com/yahoo/container/plugin/util/Maps.scala
@@ -0,0 +1,19 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.container.plugin.util
+
+import collection.mutable.MultiMap
+
+/**
+ * @author  tonytv
+ */
+object Maps {
+  def combine[K, V](map1 : Map[K, V], map2 : Map[K, V])(f : (V, V) => V) : Map[K, V] = {
+    def logicError : V = throw new RuntimeException("Logic error.")
+    def combineValues(key : K) = key -> f(map1.getOrElse(key, logicError), map2.getOrElse(key, logicError))
+
+    val keysInBoth = map1.keySet intersect map2.keySet
+    def notInBoth = !keysInBoth.contains(_ : K)
+
+    map1.filterKeys(notInBoth) ++ map2.filterKeys(notInBoth) ++ keysInBoth.map(combineValues)
+  }
+}